Selectively herbicidal 3-substituted-2-halopropyl thiolcarbamates and method of combating undesired vegetation

ABSTRACT

D R A W I N G Undesired vegetation, particularly noxious grasses in growing crops, are combated by pre-emergent application of selective herbicides made by reacting an organic compound having a reactive halogen substituent with a 2,3-epithiopropyl N,Ndialkylthiolcarbamate to yield a compound of the structural formula   IN WHICH R and R&#39;&#39; represent hydrocarbon substituents containing less than 10 carbon atoms, X is halogen, preferably bromine or chlorine and Y may be alkanoyl, chloroalkanoyl, bromoalkanoyl, alkoxyalkanoyl, N,N-dialkylcarbamyl, carbalkoxycarbonyl, alkoxymethyl, alkoxyethyl, chlorobenzoyl, bromobenzoyl, chlorophenoxyacetyl, bromophenoxyacetal, cyclopropylcarbonyl, cyano, methanesulfonyl, alkanoylmethyl alkylmercaptomethyl, nitrobenzoyl, chlorocarbalkoxyl, bromocarbalkoxyl, ethynylmethyl, dialkylphosphono, dialkylthiophosphono or alkylmercaptocarbonyl, said alkanoyl, alkoxy, carbalkoxy and alkyl structures containing less than 10 carbon atoms.

United States Patent William C. Doyle, Jr.

Leawood, Kans.

Aug. 19, 1969 Dec. 21 197 1 Gulf Research 8: Development CompanyPittsburgh, Pa.

Continuation-impart of application Ser. No. 625,603, Mar. 24, 1967, nowPatent No. 3,510,290. This application Aug. 19, 1969, Ser. No. 851,432

[72] Inventor [21 Appl. No. [22] Filed [45] Patented [73] Assignee [54]SELECTIVELY HERBICIDAL 3-SUBSTlTUTED-2- HALOPROPYL Tl-IIOLCARBAMATES ANDMETHOD OF COMBATING UNDESIRED Primary Examiner-James 0. Thomas, Jr.Attorneys-Richard L. Kelly, Carl A. Cline, Forrest D. Stine and RichardA. Anderson ABSTRACT: Undesired vegetation, particularly noxious grassesin growing crops, are combated by pre-emergent application of selectiveherbicides made by reacting an organic compound having a reactivehalogen substituent with a 2,3- epithiopropyl N,N-dialkylthiolcarbamateto yield a compound of the structural formula in which R and R representhydrocarbon substituents containing less than 10 carbon atoms, X ishalogen, preferably bromine or chlorine and Y may be alkanoyl,chloroalkanoyl, bromoalkanoyl, alkoxyalkanoyl, N,N-dialkylcarbamyl,carbalkoxycarbonyl, alkoxymethyl, alkoxyethyl, chlorobenzoyl,bromobenzoyl, chlorophenoxyacetyl, bromophenoxyacetal,cyclopropylcarbonyl, cyano, methanesulfonyl, alkanoylmethylalkylmercaptomethyl, nitrobenzoyl, chlorocarbalkoxyl, bromocarbalkoxyl,ethynylmethyl, dialkylphosphono, dialkylthiophosphono oralkylmercaptocarbonyl, said alkanoyl, alkoxy, carbalkoxy and alkylstructures containing less than l0 carbon atoms.

SELECTIVELY HERBICIDAL 3-SUBSTlTUTED-2- HALOPROPYL THIOLCARBAMATES ANDMETHOD OF COMBATING UNDESIRED VEGETATION This application is acontinuation-in-part of U.S. Ser. No. 625,603 filed on Mar. 24, 1967 nowU.S. Pat. No. 3,510,290.

DESCRIPTION OF THE INVENTION The prior application is directed to twonovel classes of herbicides (II and Ill) synthesized by means of thereactions illustrated by means of structural formulas as follows:

It was disclosed in the prior application that both II and I]! can bereacted with acetyl chloride to yield products which have identical NMRspectra and it was postulated that both products are the same compoundhaving the following structural formula:

compounds of the type represented by structural formula III may bereacted with organic compounds having reactive halogen substituents toyield a new class of selective herbicides having the generic structuralformula:

in which R and R represent hydrocarbon substituents containing less thanl0 carbon atoms, X is halogen, preferably bromine or chlorine and Y maybe alkanoyl, chloroalkanoyl. bromoalkanoyl, alkoxyalkanoyl,N,N-dialkylcarbamyl, carbalkoxycarbonyl alkoxymethyl, alkoxyethyl,halobenzoyl, halophenoxyacetyl, cyclopropylcarbonyl, cyano,methanesulfonyl, alkanoylmethyl, alkylmercaptomethyl, nitrobenzoyl,halocarbalkoxyl, ethynylmethyl, dialkylphosphono, dialkylthiophosphonoor alkylmercaptocarbonyl, said alkanoyl, alkyl, alkoxy and carbalkoxygroups containing less than carbon atoms.

A great deal of variation is possible in the Y substituent of the abovegeneral formula, so as to vary the physical and biochemical propertiesof the new class of herbicides. In the discussion below there arepresented data which show variation in phytotoxicity ranging frompre-emergent action selective to one or two particular grasses to broadactivity, both post and pre-emergent, toward many species, withrelatively less activity toward a small number of crops. The criticalfactor in successful preparation of this class of herbicides appears tobe the use of an organohalogen compound having a sufficiently reactivehalogen-to-carbon bond. This puts practical limits on choice of the Ygroups, which, of course, is the organic nucleus to which the reactivehalogen is attached.

Active halogen compounds which may be used include cyanogen halides,alkanesulfonyl halides, alpha-haloethers, propargyl halides,alpha-haloketones and halothioethers, acid halides of both aliphatic andaromatic carboxylic acids.

l DlSCUSSlON OF METHOD OF SYNTHESIS OF THE HERBlClDES Below arepresented suggested procedures for synthesis of the epithiopropylN,N-dialkyl-thilcarbamates, as well as illustrative procedures forpreparation of the herbicides of this invention by reaction with activehalogen compounds.

The 2,3- epithiopropyl N,N-dialkyl-thiolcarbamates may be prepared bytwo'general methods, one a three-step process, with isolation ofintermediates and the other essentially a single-step process, asillustrated below:

The initial low-temperature reaction is believed to include reaction ofepichlorohydrin with N,N-dialkyldithiocarbamic acid.

METHOD B The reaction of epichlorohydrin with a salt (which may also bea metal salt, as well as an amine salt) appears to require a highertemperature than reaction with the acid.

In an experiment in which both routes were used to prepare the sameN,N-diethyl thiolcarbamate compound, the yields were roughly equivalent.ln syntheses based on morpholine, dicylclohexylamine or isopropylcyclohexylamine as starting materials, Method B has been found to be theonly successful route, with the dithiocarbamate salt being the soleproduct obtained in the first step of method A, rather than the morereactive free acid.

Intermediates (l) and (ll) are capable of isolation but are not easilypurified. Compound (I) is thermally unstable, rearranging to (ll) in amatter of several hours to several days, depending on the nature of theN substituents. The structure of (l) is thought to be as shown,'based onits infrared spectrum and the NMR spectrum of its phenylurethanederivative. intermediate compounds (II) are relatively stable andsuitable for use in manufacturing the herbicides of this invention,although use of the more stable epithiopropyl compounds (lll) ispreferred. Present evidence favors the structure of 11 shown in thereaction diagram below, which shows schematically the treatment withacetyl chloride of both compounds (ll) and (lll) to give compounds oftype (W).

O R O S RN H N scmcncmsn NOSOHrCH-CH R II E III 011.0001 01;,0001 i i i1Neeomouomscoizr The success of the sequence of reactions leading to anepithiopropyl thiolcarbamate apparently requires a secondary amine asstarting material. In three instances in which a primary amine was usedthe crude products decomposed extensively and no epithiopropylthiolcarbamate (III), was obtained. In one experiment, starting withtert.-buty1 amine, tert.-butyl isothiocyanate was found among theproducts of decomposi tion.

The epithiopropyl thiocarbamate products (111) of the sequence aredistillable liquids or crystalline solids. Some care must be exercisedto prevent excessive heating during distilla tion. Otherwise thefollowing decomposition readily occurs:

R fl) S R h) The 3-substituted-IZ-halopropyl thiolcarbamates asillustrated by (IV) above are generally liquids at room temperature andare stable in storage, but resemble compounds of type (III) insensitivity to heating.

II ILLUSTRATIVE PROCEDURES Method A To a well-stirred mixture of 38.0 g.(0.5 mol) of carbon disulfide and 46.3 g. (0.5 mol) of epichlorohydrinin an icesalt bath is added 36.5 g. (0.5 mol) of anhydrous diethylamineduring 1-2 hours at to -5 C. The mixture is stirred an additional 30minutes, then let warm slowly to room temperature. At this point thereaction mixture is essentially 3-chloro-2- hydroxypropylN,N-diethyldithiocarbamate, (1; R,1R'=Et), a viscous yellow oil with nodetectable unreacted starting materials present.

Heating of the reaction mixture for 2 hours at 80-90 under vacuum gives1 g. of crude rearrangement product 11 (R.R'=Et). the course of therearrangement may be easily followed by the disappearance of infraredabsorption bands at 2.95 pt (OH) and 10.15 ,u (C=S) and with theappearance of bands at 3.92 [1. (SH) and 6.0 [.L (C =0). Therearrangement is also accompanied by a marked decrease in viscosity.

To 29 g. (0.12 mole ofthe crude rearranged product in 100 ml. of etheris added slowly 12 g. (0.12 mols of triethylamine. Reaction isimmediate, causing the ether to reflux gently and precipitating 10.8 g.of triethylamine hydrochloride. The solution is filtered, evaporated andvacuum distilled, giving 15.1 g. (61.4 percent yield overall) of2,3epithiopropyl N,N-diethylthiolcarbamate (Ill; R,R'=Et),

b.p.0.2 mm.l19-20.

MethodB A solution of 36 g. (0.173 mol) of diethylammoniumdiethyldithiocarbamate and 15.0 g. (0.162 mols) of epichlorohydrin in100 ml. of dioxane is heated to reflux. Shortly after heating is begun,a crystalline precipitate appears. After 2 hours, the solution is cooledand filtered to recover 15.4 g. of diethylamine hydrochloride. Thefiltrate is vacuum distilled to remove the bulk of the solvent, leaving33.2 g. ofa viscous brown oil. Extraction of this oil with ether.decantation and evaporation of the ether gives 25.7 g. of residue,distillation of which gives 17.7 g. of a compound of type (III) in whichR and R are ethyl.

The procedures illustrated may be used with various secondary amines ordithiocarbamates as starting materials to produce the desiredepithiopropyl thiocarbamates, method A being generally more desirablebecause it employs cheaper raw materials and generally gives goodyields. Below are presented illustrative examples of syntheses of3-organothio- 2-halopropy1 N,N-disubstituted thiolcarbamates of thisinvention.

Preparation of 3-acetylthio-2-chloropropyl N,N-diethyl thiolcarbarnatell mmcscmcrr crn CHiCCl 11 I 9 1| sync s omcncms com A mixture of 16. 4g. (0.08 mole) of 2,3-epithiopropyl N,N- diethylthiolcarbamate and 6.3g. (0.08 mole) of acetyl chloride is heated 5.5 hours on the steam bathunder reflux and then distilled at reduced pressure. Following a shortforerun, there is obtained 3.4 g. of an intermediate cut, b.p. 133-140C.at 0.07 mm. and 10.8 g. of 3-acety1thi0-2 chloropropylN,N-diethylthiolcarbamate, b.p. 1405 C. at

0.05 mm. N26 1.5302.

Preparation of 3-cyclopropanecarbonylthio-Z-chloropropylN,Ndiethylthiolcarbamate I 11 EtiNC S CHiCHCHzS C l A mixture of 10.3 g.(0.05 mole) of 2,3-epithiopropyl N,N- diethylthiolcarbamate and 5.2 g.(0.05 mole) of cyclopropanecarbonyl chloride is heated 20 hours on thesteam bath and then vacuum stripped at 120 C. pot tempera ture and 0.1mm. pressure giving as the residual oil, 14.2 g. of3-cyclopropanecarbonylthio-Z-chloropropyl N,N-diethy1thiol carbamate,N26 1.5378.

Preparation of 3-Thiocyano-2-bromopropyl N.N-

Dipropylthiolcarbamate 11 PrzNC S CHzCHCHzS ON 1| PrzNCSCIIgCII -CH2CHgOCHrCl 11 lrzNC S CHzJJHCHiS CHiOCHa A mixture of 23.3 g. (0.1 mol)of 2,3-epithiopropyl N,N- dipropylthiolcarbamate and 8.1 g. (0.1 mol) ofchloromethyl methyl ether is heated 2 hours at 60under a refluxcondenser and then vacuum stripped at pot temperature and 0.1 mm.pressure to give 30.5 g. of 3methoxymethylthio-2- chloropropylN,N-dipropylthiolcarbamate.

Tabulated below are chemical and physical properties of specificproducts obtained by the procedures discussed and illustrated above.

TABLE 1.-PROPERTIES OF PRODUCTS F FORMULA RR'NCOS-CH2OXHCH:S-Y

Anal sis Found Calculated Compound No. R and R X-Y nCaH-r 8 IlCaHI I0-0H.0 CH;

10 IICaH7 H Br-C-CHzBr 14... nCaHy A 4.15 10. 4g 49. go

I Ol-C C1C-CHa O CH 3 Analysis Calculated Found 49. 41 5. l2 3. 39 34.33 43. SO 43. 3. 28 31.

ND/ C. or (B.P.lmm.)

Compound No.

32... isoC H1 38 ............isoCaII1 iS0C3H1 isoCaIh 44 n-CaHy n-CaH77. 4.2 4. an 10. as 48. 40

a. us a. a2 7. 34 42. 32

53.. .1l-C:U1

54.... n-C3H1 n1. HERBlClDAL USE A. Post Emergent Activity An aqueousdispersion of each active compound was prepared by combining 0.4 gram ofthe compound with about 4 ml. of a solvent-emulsifier mixture (3 partsof a commercial polyoxyethylated vegetable oil emulsifier, one partexylene, one part kerosene) and then adding water, with stirring, to afinal volume of 40 ml.

The species of plants on which each compound was to he tested wereplanted in 4-inch pots in a greenhouse. Ten to 18 days after emergenceof the plants} three pots were sprayed with an aqueous dispersion of theactive compound prepared as described above, at a rate of 5 lb. ofactive compound per acre and at a spray volume of 60 gallons per acre.Approximately 1 week after the spray application the plantswere observedand the results rated according to the following schedule:

Herbicidal Effect no effect I slight effect 2 moderate effect B.Pre-emergent Activity A solution of each active compound was prepared bydissolving 290 mg. of the compound to be tested in 200 ml. of acetone.Disposable paper half-flats (molded pulp trays about 2 to 3 inchesdeep-and half the size of ordinary greenhouse flats) were prepared andseeded with a variety of species of plant seeds, then sprayed with theacetone solution at the rate of lb. of active chemical per acre ofsprayed area. One flat, which has been seeded with alfalfa, brome, flax,oats, radishes andsugar beets were held at F. day temperature; anotherseeded with corn, coxcomb, cotton, crab grass. millet and soybeans washeld at F. Twenty-one days after seeding and treatment the flats wereexamined and herbicidal effect was TABLE 2.-PRE- AND POST-EMERGENTHERBICIDAL ACTIVITY Grain Compound Crab- Cox- Soy- Cot- 7 Sugar 801'-No. Type grass comb Brome Millet bean ton Alfalfa Oats Corn Flax Radish,beet Wheat ghum Tomato 1 {Pre 2 0 4 1 0 0 0 3 '0 0 0 0 Post.. 0 2 0 0 01 0 0 0 0 0 0 Pre--- 1 0 4 2 1 1 0 2 0 0 0 1 1 0 1 0 0 0 1 1 1 0 0 l 4 21 1 4 0 1 3 1 0 0 0 0 0 0 0 0 0 0 J 0 2 0 0v 0 3 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 l 0 0 0 l 0 0 0 0 0 0 1 0 0 0 1 0 2 0 0 0 2 0 0 0 3 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0 2 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 1 0 0 0 0 0 0 0 0 0 0 0 1 0 1 3 2 2 00 2 1 0 0 1 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 3 0 0 0 0 0 0 0 00 0 0 0 0 0 l) 0 1 0 0 0 4 0 l l 1 0 0 0 0 0 0 0 0 0 0 0 0 2 1 0 0 3 0 00 0 0 O 0 0 0 0 0 0 0 0 0 0 1 -0 0 0 2 0 0 0 0 '0 0 0 0 0 0 0 -0 0 0 0 02 1 3 0 2 0 0 0 1 1 0 1 0 0 0 0 0 1 0 0 0 3 1 1 1 4 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 4 4 4 4 4 3 4 4 4 2 4 4 4 1 2 4 4 4 1 1 4 4 4 4 4 3 3 4 4 43 4 4 4 3 3 4 4 4 2 2 4 3 4 4 4 4 3 4 4 4 0 3 3 2 2 0 3 1 3 0 0 4 2 2 00 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 1 1 0 4 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 2 1 1 0 4 0 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 3 0 0 0 4 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 3 1 0 0 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 i 0 0 3 0 0 0 40 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 1 0 0 3 0 0 0 0 0 O 0 0 0 0 0 0 0 0 00 2 1 0 0 4 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 2 1 0 0 3 0 0 0 0 0 0 0 0 00 0 0 0 0 (l 0 2 l 0 0 4 0 0 0 0 0 0 0 0 O 0 0 0 0 0 0 0 1 2 0 l 4 0 0 00 o 0 0 7. .0 0 0 0. 0 V 0

2. The method of combating undesired vegetation which comprises applyingto the locus of seeds of the undesired vegetation an effective amount of3-cyclopropanecarbonylthio-2-chloropropyl N,N-diisopropylthiolcarbamate.
 3. The method of combating undesiredvegetation which comprises applying to the locus of seeds of theundesired vegetation an effective Amount of3-isobutyrylthio-2-chloropropyl N,N-dipropylthiolcarbamate.
 4. Themethod of combating undesired vegetation which comprises applying to thelocus of seeds of the undesired vegetation an effective amount of3''-propanoylthio-2-chloropropyl N,N-dipropylthiolcarbamate.
 5. Themethod of combating undesired vegetation which comprises applying to thelocus of seeds of the undesired vegetation an effective amount of3-propanoylthio-2-chloropropyl N,N-diisopropylthiolcarbamate.
 6. Themethod of combating undesired vegetation which comprises applying to thelocus of seeds of the undesired vegetation an effective amount of3-isovalerylthio-2-chloroprooyl N,N-diisopropylthiolcarbamate.
 7. Themethod of combating undesired vegetation which comprises applying to thelocus of seeds of the undesired vegetation an effective amount of3-isobutyrylthio-2-chloropropyl N,N-diisopropylthiolcarbamate.
 8. Themethod of combating undesired vegetation which comprises applying to thelocus of seeds of the undesired vegetation an effective amount of3-butyrylthio-2-chloropropyl N,N-diisopropylthiolcarbamate.